1. Field of the Invention
The present invention relates to mobile devices. More particularly, the present invention relates to a mobile device comprising a disk storage system protected by a pressure-sensitive detector.
2. Description of the Prior Art
Integrating a disk storage system into a mobile device (e.g., a handheld computer such as a personal digital assistant (PDA), cellular phone, digital camera, tablet computer, etc.) provides a significant amount of non-volatile data storage for a relatively low cost. A disk storage system comprises a head flying just above the surface of a rotating disk. The head is attached to the distal end of an actuator arm which is rotated about a pivot by a voice coil motor in order to actuate the head over the disk. The disk comprises a magnetic coating which is magnetized by an inductive element in the head in order to write magnetic transitions onto the surface of the disk representing the recorded data. During a read operation, a read element in the head (e.g., inductive or magnetoresistive) detects the magnetic transitions to generate a read signal that is demodulated into an estimated data sequence representing the recorded digital data. Physical shocks can cause the head and actuator arm assembly to deviate off track and over-write data in adjacent tracks before the servo system detects the error. In addition, the head and the media can be damaged if the head xe2x80x9cslapsxe2x80x9d onto the surface of the disk. Physical shocks due to being dropped are of particular concern for mobile devices.
There is, therefore, a need to detect when a mobile device may have been dropped so that protective measures can be taken to prevent damage to the heads or media of a disk storage system incorporated into the mobile device.
The present invention may be regarded as a mobile device comprising a disk storage system including a disk and a head actuated over the disk, wherein the disk comprises a data area. The mobile device further comprises a pressure-sensitive detector for detecting a pressure on the mobile device, and for detecting a decrease in the pressure indicating the mobile device may have been dropped. When the pressure-sensitive detector detects the decrease in the pressure, retracting circuitry within the mobile device retracts the head to a retracted position away from the data area of the disk.
In one embodiment the head retracting circuit retracts the head to the retracted position when the pressure decreases substantially to zero.
In another embodiment, the pressure-sensitive detector comprises a first terminal and a second terminal, the pressure is detected when the terminals are pressed together, and the decrease in the pressure is detected when the terminals separate. In alternative embodiment, the pressure-sensitive detector comprises a piezoelectric sensor comprising at least one piezoresistor, wherein the resistance of the piezoresistor changes when pressure is applied to the piezoelectric sensor. In an alternative embodiment, the pressure-sensitive detector comprises a force sensor, such as a polymer layer disposed between a first and second conductive layers.
In yet another embodiment, the mobile device comprises a timer for timing a predetermined interval, wherein at the end of the predetermined interval the head is actuated away from the retracted position toward the data area of the disk. In an alternative embodiment, the head is locked in the retracted position until the pressure-sensitive detector detects the pressure on the mobile device.
In one embodiment, the pressure is due to a user holding the mobile device. In still another embodiment, the pressure is due to the mobile device contacting a surface (such as a desk).
In another embodiment, the mobile device comprises interface circuitry for connecting to a docking port, and the pressure-sensitive detector is disabled while the mobile device is connected to the docking port.
The present invention may also be regarded as a method of operating a mobile device comprising a disk storage system including a disk and a head actuated over the disk, wherein the disk comprises a data area. The method comprises the steps of detecting a pressure on the mobile device, detecting a decrease in the pressure on the mobile device indicating the mobile device may have been dropped, and retracting the head to a retracted position away from the data area of the disk when the decrease in the pressure is detected.
The present invention may also be regarded as a mobile device comprising a disk storage system comprising a disk, a head actuated over the disk, and a preamp for applying a write current to the head during a write operation. The mobile device further comprises a pressure-sensitive detector for detecting a pressure on the mobile device, and for detecting a decrease in the pressure on the mobile device indicating the mobile device may have been dropped, wherein when the decrease in the pressure is detected the write current is disabled.
The present invention may also be regarded as a method of operating a mobile device comprising a disk storage system comprising a disk and a head actuated over the disk, wherein a write current is applied to the head during a write operation. The method comprises the steps of detecting a pressure on the mobile device, detecting a decrease in the pressure on the mobile device indicating the mobile device may have been dropped, and disabling the write current when the decrease in the pressure is detected.